Title : Antimicrobial resistance of listeria monocytogenes in meat-based ready-to-eat products from Romania: Implications for public health
Abstract:
Listeria monocytogenes remains a major concern for food safety, particularly in meat-based ready-to-eat (RTE) products that are consumed without further heat treatment. This study focused on the occurrence, virulence characteristics, and antimicrobial resistance of L. monocytogenes isolated specifically from meat-derived RTE foods in northwestern Romania between 2019 and 2022.
Out of 8,151 RTE samples analyzed, contamination was predominantly associated with pork and fish products, indicating meat as the primary source of L. monocytogenes isolation. A total of 26 strains were identified, with a marked increase in detection during 2022. Serotyping revealed that the majority of isolates belonged to serotype 1/2a, followed by 1/2b and 1/2c—serotypes commonly linked to human listeriosis.
All isolates carried essential virulence genes, including hlyA and prfA, confirming their pathogenic potential. Notably, strains isolated in 2022 exhibited a broader virulence profile, testing positive for all investigated virulence determinants, suggesting a possible increase in pathogenicity over time within meat-associated strains.
Antimicrobial susceptibility testing revealed significant resistance to trimethoprim-sulfamethoxazole (26.92%) and oxacillin (23.07%). Additionally, a concerning proportion of isolates (23.07%) displayed multidrug resistance, most frequently involving resistance to oxacillin, penicillin, and tetracycline. Despite this, all strains remained susceptible to fluoroquinolones such as ciprofloxacin, levofloxacin, and moxifloxacin. Molecular analysis identified a high prevalence of tetracycline resistance genes (tet(C), tet(M), tet(K)) as well as ampC and dfrD, indicating the presence of multiple resistance mechanisms in meat-derived isolates.
These findings emphasize that meat-based RTE products, particularly pork, represent a significant reservoir for virulent and antimicrobial-resistant L. monocytogenes in Romania. Strengthened monitoring and targeted control strategies in meat processing environments are essential to reduce contamination risks and protect public health.
